5 Electricity and Magnetism
5.1 Electric Charge and Electric Field
Coulomb's law / image charge
P2420401
Relationship between electrostatic force F and
the square of the charge Q for various distances
(a) between ball and plate.
Principle
DC measuring amplifier
A small electrically charged ball is positioned at a certain distance
in front of a metal plate lying at earth potential. The surface
charge on the plate due to electrostatic induction together with
the charged ball forms an electricfield analogous to that which exists between two oppositely charged point charges. The electrostatic force acting on the ball can be measured with a sensitive
torsion dynamometer.
Tasks
1. Establishment of the relation between the active force and
the charge on the ball.
2. Establishment of the relation between force and distance,
ball to metal plate.
3. Determination of the electric constant.
What you can learn about
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Electric field
Electric field strength
Electric flux
Electrostatic induction
Electric constant
Surface charge density
Dielectric displacement
Electrostatic potential
Versatile measuring amplifier for measurement of very small direct
currents, electrical charges and for quasi-static measurements of
DC voltages.
Equipment and technical data
▪ 8 current measurement ranges with very low voltage drop
▪ 6 voltage measurement ranges with extremely high input resistance, 5 charge measurement ranges
▪ Analogue output for connection of demonstration measurement instruments/ pen recorders, button for reversing output
voltage
▪ Selection of measurement modes using push-button
▪ Diode indicators for active measurement range
▪ Zero point adjustment, discharge button, range selection buttons
Current measurement
▪ Measurement range: 0.01 nA...0.1 mA in 8 decade ranges,
Voltage drop: 1 mV
Voltage measurement
▪ Measurement range: 0.1 mV...10 V in 6 decade ranges
▪ Input resistance: 10 gOhm
Main articles
DC measuring amplifier
Power supply, high voltage, 0-25 kV
Torsion dynamometer, 0.01 N
Plate capacitor, 283x283 mm
Function and Applications
13620-93
13671-93
02416-00
06233-02
1
1
1
4
Charge measurement
▪ Measurement range: 0.1 nAs...0.001 mAs in 5 decade ranges
▪ Accuracy: 3%, Input: BNC socket, Overload protection: 250 V
13620-93
PHYWE Systeme GmbH & Co. KG · www.phywe.com
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